1. Field of the Invention
The present invention relates in general to web processing units, and in specific, to web processing units capable of processing variable document lengths, at high web speed, with a simple programmable adjustment.
2. Description of the Prior Art
The present method of achieving variable document length on high speed printers, capable of handling a web speed of 500 to 1500 feet per minute, is to physically change their operating cylinders or rings. A cylinder or ring having a particular circumference or having a particular number of processing tools around the circumference must be installed for each desired document length. This cylinder or ring must then be replaced for each change in document length.
Other web processors known in the art use intermittent web motion with variable tool stroke through part of the press and constant web speed in the other parts. However, these presses are relegated to slow speed operation due to their intermittent motion. Other models use intermittent variable stroke web motion. This method is intrinsically slow and unsuitable to volume production of documents.
This invention corrects the shortcomings of the prior art methods, enabling documents of various lengths to be processed, at high speed, with only programmable changes. The web processor can rapidly and automatically be adjusted and accommodated to various document lengths.